Traditionally, inhalation therapy has played a relatively minor role in the administration of conventional pharmaceuticals compared to more conventional drug administration routes, such as oral and intravenous. However, oral and intravenous routes have many disadvantages, and alternative administration routes are needed. Inhalation is one such alternative administration route. Various approaches to attain inhalation type compositions are nebulizers, pressurized metered dose inhalers (pMDI) and dry powder inhalers (DPI).
A DPI has advantages over pMDIs for the delivery of inhaled drugs to pediatric and geriatric patients. Many pediatric and geriatric patients have difficulty using a pMDI correctly, because of the high speed at which each dose is delivered and, hence have issues following the inhalation procedure recommended in the Patient Information Leaflet. In order to deliver the drug effectively into the lung, the patient must actuate the pMDI as they start to inhale. This needs a high degree of ‘hand/lung’ co-ordination and failure to achieve this often results in reduced effectiveness of treatment and poor disease control. However, when using DPIs, the patient must generate sufficient inspiratory effort to ensure that the dose emitted from a DPI device contains drug particles that have the greatest potential to be delivered to the conducting airways. The faster the inspiration rate through the DPI, the better is the quality of the emitted dose for lung deposition. This applies to all DPIs, but for some the effect is minimal, whereas other DPIs show significant flow-dependent dose emission, which may result in erratic dose emission and in turn compromise consistent disease control.
The variety of DPIs that are currently available come in three device categories: single dose inhalers in which each dose is loaded into the device before use; multi dose reservoir inhalers in which a bulk supply of medicament is preloaded into the device and multiple unit-dose inhalers in which several single doses are individually sealed and a single dose is then discharged each time the device is actuated. In the case of multi dose inhalers, once all doses have been used the entire device is disposed of and a new device obtained. Nevertheless, disposing of the entire device, particularly a complex device, when empty may have cost implications, so refillable devices have been developed. For such refillable devices a component of the device must be replaced or refilled when required and only the empty or no longer useable part will be disposed of.
The DPI device which is sold by Glaxo Smith Kline under the trade name Diskus® is one of the renowned multi-unit-dose dry powder inhalers in the market. In Diskus DPI device, the dry powder medicament is carried in cavities which are placed along the blister strip. The mouthpiece and lever appear by moving the mouthpiece cover to its open position. The lever associated with the finger tab, actuates the gear mechanism as the finger tab is slid from end to end. Hence, the blister strip is advanced, one blister is opened, and one dose of the dry powder medicament contained in the blister cavity, becomes ready for the inhalation.
U.S. Pat. Nos. 5,873,360, 8,161,968, 8,499,758 and 8,051,851 disclose various dry powder inhaler devices.
Most of the known inhaler devices have some limitations such as bulkiness, complex to assemble or non-robust structures.
There is a need for a multiple unit-dose dry powder inhaler which is simple, easy to assemble, robust to use and suitable for delivering accurate doses in different ranges of inspiratory capacity, easy and hygienic to use, cost effective and optionally reusable.